Research On Preparation Process And Thermal Properties Of Si-Coated Diamond/Al Composites

With the development of high power laser,the heat generated by laser increases greatly.The stability and reliability of the laser will be affected by heat accumulation.Therefore,solving the problem of heat dissipation of the laser device is particularly prominent and important,which the performance of electronic packaging materials,put forward new requirements.The traditional thermal management materials are limited to the material thermal expansion coefficient,thermal conductivity and density and other properties,can not meet the current development of the semiconductor industry.Diamond material has been widely used in the field of thermal management materials because of its excellent thermal physical properties and production cost.However,due to diamond and metal copper between high-temperature wettability is poor,and copper matrix density,in humid air of poor corrosion resistance characteristics,thus the present development phase of diamond metal matrix composites mainly concentrated in diamond/Al composites.In this paper,we used two different surface modification methods to modify the surface of diamond particles.Scanning electron microscopy,Raman spectroscopy,transmission electron microscopy,X-ray photoelectron spectroscopy and other test techniques have been used to analysis and research the micro morphology and structure of the surface of diamond particlesThis paper adopts the method of high temperature salt bath,the diamond particles were plated with silicon.By scanning electron microscopy?SEM?,X ray diffraction?XRD?and focused ion beam?FIB?characterization and analysis of test characterization methods on diamond surface morphology and structure.?1?The high temperature molten salt bath on diamond surface by coating silicon processing,when the processing temperature is 1200 °C,Si layer thickness is uniform,with a thickness of about 300 nm.Diamond coatings on silicon surfaces make it different from uncoated silicon on diamond surface selective adhesion,on all sides have aluminum adhesion,between diamond and aluminum substrate has a good interfacial bonding,composite matrix fracture is the main method of fracture at the interface SiC-Si-Al layer had no Al₄C₃ formation,diamond / Al composites interface binding is enhanced,and improve the thermal conductivity of the composites.By squeeze casting preparation of diamond / Al composites,under the same volume fraction of diamond,silicon coating layer of diamond composite material thermal conductivity rate almost reached that of uncoated diamond silicon composite twice,605 W/?m·K?.?2?Surface plating silicon diamond powder and electrolytic aluminum powder mixing,diamond / Al composites were prepared by different hot pressing parameters,determining the optimum parameters for hot pressing,when the volume fraction of diamond is 45%,the thermal conductivity of the composite rate reaches the maximum,for 558 W/?m·K?.For the diamond reinforced metal matrix composites with high phase difference,the DEM model can predict the experimental results more accurately than the Hasselman-Johnson model.When the difference is greater than 2,the thermal conductivity model ofHasselman-Johnson and DEM has a significant difference.When the content of diamond is less than 50%,the DEM model can predict the experimental results well.